Basket catheter with improved spine flexibility

ABSTRACT

A catheter with basket-shaped electrode assembly with spines configured for hyper-flexing in a predetermined, predictable manner when a compressive force acts on the assembly from either its distal end or its proximal end. At least one spine has at least one region of greater (or hyper) flexibility that allows the electrode assembly to deform, for example, compress, for absorbing and dampening excessive force that may otherwise cause damage or injury to tissue wall in contact with the assembly, without compromising the structure and stiffness of the remaining regions of the spine, including its distal and proximal regions. The one or more regions of greater flexibility in the spine allow the spine to flex into a generally V-shape configuration or a generally U-shape configuration.

This application is a continuation of and claims priority to and thebenefit of U.S. application Ser. No. 16/267,271 filed Feb. 4, 2019, nowU.S. Pat. No. 10,582,871, which is a continuation of and claims priorityto and the benefit of U.S. application Ser. No. 15/728,401 filed Oct. 9,2017, issued as U.S. Pat. No. 10,194,818, which is a continuation of andclaims priority to and the benefit of U.S. application Ser. No.14/587,497 filed Dec. 31, 2014, issued U.S. Pat. No. 9,782,099, theentire contents of all of which are incorporated herein by reference.

FIELD OF INVENTION Field of Invention

This invention relates to electrophysiologic (EP) catheters, inparticular, EP catheters for mapping and/or ablation in the heart.

Background

Electrophysiology catheters are commonly-used for mapping electricalactivity in the heart. Various electrode designs are known for differentpurposes. In particular, catheters having basket-shaped electrode arraysare known and described, for example, in U.S. Pat. Nos. 5,772,590,6,748,255 and 6,973,340, the entire disclosures of both of which areincorporated herein by reference.

Basket catheters typically have an elongated catheter body and abasket-shaped electrode assembly mounted at the distal end of thecatheter body. The assembly has proximal and distal ends and comprises aplurality of spines connected at their proximal and distal ends. Eachspine comprises at least one electrode. The assembly has an axialelongated expander which is longitudinally movable relative to thecatheter by an EP professional to vary the configuration of the basketbetween an expanded arrangement wherein the spines bow radiallyoutwardly and a collapsed arrangement wherein the spines are arrangedgenerally along the axis of the catheter body. The catheter may furthercomprise a distal location sensor mounted at or near the distal end ofthe basket-shaped electrode assembly and a proximal location sensormounted at or near the proximal end of the basket-shaped electrodeassembly. In use, the coordinates of the distal location sensor relativeto those of the proximal sensor can be determined and taken togetherwith known information pertaining to the curvature of the spines of theassembly to find the positions of the at least one electrode of eachspine.

A basket-shaped electrode assembly is capable of detecting in a singlebeat most or all of the electrical function of the left or right atrium.However, because the atria of an individual patient may vary in size andshape, it is desirable that the assembly be sufficiently versatile andsteerable to conform to the particular atrium. A basket catheter with adeflectable assembly for improved maneuverability to provide bettertissue contact, especially in a cavernous region of the heart, includingan atrium, is described in U.S. Pat. No. 9,204,929 (corresponding toapplication Ser. No. 14/028,435, filed Sep. 16, 2013), the entiredisclosure of which is hereby incorporated by reference.

While a deflectable basket catheter whose basket configuration can bevaried by an expander enables an EP professional to adjust the basketfor a better fit within any particular atrium, a basket with stifferspines may enable better contact between the spines and the atrial wall.However, stiffer spines may increase the risk of injury and damage tothe atrial wall.

Nitinol wire is often used in the construction of therapeutic anddiagnostic catheter distal ends, including basket-shaped electrodeassemblies. At body temperature, nitinol wire is flexible and elasticand like most metals nitinol wires deform when subjected to minimalforce and return to their shape in the absence of that force.Accordingly, a 3-D distal assembly can be easily collapsed to be fedinto a guiding sheath, and readily deployed in the chamber or tubularregion upon removal of the guiding sheath. Because Nitinol belongs to aclass of materials called Shaped Memory Alloys (SMA). These materialshave interesting mechanical properties beyond flexibility andelasticity, including shape memory and superelasticity which allownitinol to have a “memorized shape.”

Nitinol has different temperature phases, including martensitic phaseand austenite phase. The austenite phase is Nitinol's stronger,higher-temperature phase. Crystalline structure is simple cubic.Superelastic behavior occurs in this phase (over a 50°-60° C.temperature spread). The Martensite phase is Nitinol's weaker,lower-temperature phase. Crystalline structure is twinned. Material iseasily deformed in this phase. Once deformed in martensite, it willremain deformed until heated to austenite where it will return to itspre-deformed shape, producing the “shape memory” effect. The temperatureat which Nitinol starts to transform to austenite upon heating isreferred to as the “As” temperature. The temperature at which Nitinolhas finished transforming to austenite upon heating is referred to asthe “Af” temperature.

Accordingly, it is desirable that a basket catheter have spines that aresufficiently pliable and flexible to minimize the risk of injury anddamage to the atrial wall, yet provide sufficient stiffness fordependable tissue contact and electrode spacing. It is also desirablethat a basket catheter have spines constructed of material with shapememory, such as nitinol, so as to employ some of its advantageousproperties.

SUMMARY OF THE INVENTION

The present invention is directed to a catheter with a basket-shapedelectrode assembly configured to adopt a collapsed configuration, anexpanded configuration and a hyper-expanded configuration. The assemblyhas spines with portions of greater (hyper) flexibility, and portions oflesser flexibility by comparison, for enabling dependable tissue contactand electrode space, without increasing the risk of tissue damage. Inaccordance with a feature of the present invention, one or more spinesof the assembly are shaped to deform in a predetermined manner and/or atpredetermined locations with greater predictability in response to anaxial force acting on the assembly from either its distal end or itsproximal end. Advantageously, the spines readily flex in the portions ofgreater flexibility much like “shock absorbers,” enabling the assemblyto compress axially and absorb and dampening forces that may otherwisedamage tissue, yet retain sufficient shape and rigidity for ensuringcontact with tissue wall and electrode space. In some embodiments, aportion of greater flexibility in the spine has a smaller cross-section,for example, a lesser thickness and/or a lesser width relative to theremaining portion(s) of the spine with lesser flexibility by comparison.In some embodiments, the lesser thickness and/or lesser width areprovided by one or more notches that may be oriented laterally on thespine, or on an inner or outer surface of the spine. The notch may havea generally smooth contour or a stepped contour.

In accordance with a feature of the present invention, one or morespines of the basket-shaped electrode assembly may have one or moreregions of greater flexibility that enable the assembly to compresslongitudinally in response to an axial force. In some embodiment, atleast one spine has an equatorial portion with greater flexibility, anddistal and proximal portions of the spine with lesser flexibility bycomparison, where the equatorial portion flexes more readily than thedistal and proximal portions, and the spine flexes into a V shape with agreater or acute bend in the equatorial portion. In some embodiments, aspine has first and second portions of greater flexibility separated bya mid-portion of lesser flexibility, where the first and second portionsflex more readily than the mid-portion and/or the distal and proximalportions, and the spine flexes into a U shape with two greater or acutebends between the mid-portion.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention will bebetter understood by reference to the following detailed descriptionwhen considered in conjunction with the accompanying drawings wherein:

FIG. 1 is a top plan view of a catheter of the present invention,according to one embodiment, with a basket-shaped electrode assembly inan expanded, deployed configuration.

FIG. 2 is a detailed view of the basket-shaped electrode assembly ofFIG. 1, in a collapsed configuration.

FIG. 3A is a side cross-sectional view of the catheter of the presentinvention, including a junction between a catheter body and a deflectionsection, along a diameter.

FIG. 3B is an end cross-sectional view of the deflection section of FIG.3A, taken along line B-B.

FIG. 4A is a detailed view of the basket-shaped electrode assembly ofFIG. 1, in an expanded, deployed configuration.

FIG. 4B is a side elevational view of the assembly of FIG. 4A, in ahyper-flexed configuration.

FIG. 4C is a perspective view of a cylindrical body forming spines ofthe basket-shaped electrode assembly, in accordance with one embodiment.

FIG. 5A is a top view of a cabling for use with the present invention,according to one embodiment, with part(s) broken away.

FIG. 5B is an end cross-sectional view of the cabling of FIG. 5A.

FIG. 5C is a side view of the cabling of FIG. 5A, with part(s) brokenaway.

FIG. 6A is a side cross-sectional view of a proximal junction of thebasket-shaped electrode assembly, according to one embodiment.

FIG. 6B is an end cross-section view of the proximal junction of FIG.6A, taken along line B-B.

FIG. 7A is a side cross-sectional view of a distal tip, in accordancewith one embodiment.

FIG. 7B is an end cross-sectional view of the distal tip of FIG. 7A,taken along line B-B.

FIG. 7C is an end cross-sectional view of the distal tip of FIG. 7A,taken along line C-C.

FIG. 8A is a perspective view of a spine with stepped lateral notchedregions, in accordance with an embodiment of the present invention.

FIG. 8B is a perspective view of the spine of FIG. 8A in a flexedconfiguration.

FIG. 9A is a perspective view of a spine with smooth lateral notchedregions, in accordance with an embodiment of the present invention.

FIG. 9B is a perspective view of the spine of FIG. 9A in a hyper-flexedconfiguration.

FIG. 10A is a perspective view of a spine with a smooth inner notchedregion, in accordance with an embodiment of the present invention.

FIG. 10B is a perspective view of the spine of FIG. 10A in ahyper-flexed configuration.

FIG. 11A is a perspective view of a spine with a stepped inner notchedregion, in accordance with an embodiment of the present invention.

FIG. 11B is a perspective view of the spine of FIG. 11A in ahyper-flexed configuration.

FIG. 12A is a perspective view of a spine with a stepped waist region,in accordance with an embodiment of the present invention.

FIG. 12B is a perspective view of a spine with a smooth waist region, inaccordance with an embodiment of the present invention.

FIG. 13A is a perspective view of a spine with multiple portions ofgreater flexibility, in accordance with an embodiment of the presentinvention.

FIG. 13B is a perspective view of the spine of FIG. 13A, in ahyper-flexed configuration.

FIG. 13C is a perspective view of a basket-shaped electrode assemblywith spines having multiple portions of greater flexibility, inaccordance with an embodiment of the present invention.

FIG. 13D is a side elevational view of the basket-shaped electrodeassembly of FIG. 13C, in a hyper-flexed configuration.

FIG. 14A is a side cross-sectional view of a spine with covering, inaccordance with an embodiment of the present invention.

FIG. 14B is a side cross-sectional view of the spine of FIG. 14A, in ahyper-flexed configuration.

FIG. 15A is a detailed view of a basket-shaped electrode assembly, inaccordance with another embodiment, in an expanded, deployedconfiguration.

FIG. 15B is a perspective view of the assembly of FIG. 15A, in ahyper-flexed configuration.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to a catheter 10 having abasket-shaped assembly 18 with at least a region of greater flexibilityand at least a region or portion of lesser flexibility by comparisonrelative to the region of greater flexibility which enable thebasket-shaped assembly 18 to readily flex in a predetermined manner andabsorb excessive forces that may otherwise result in injury or damage totissue, for example, when the assembly 18 unexpectedly encountersanatomy or when the assembly 18 is pressed excessively against tissue.The catheter of the present invention provides this flexibility withoutsignificant compromise in the shape, structure and sufficient rigidityof the assembly in providing dependable tissue contact and electrodespacing.

As shown in FIG. 1, the catheter 10 comprises an elongated catheter body12 having proximal and distal ends, a control handle 16 at the proximalend of the catheter body, an intermediate deflection section 14 distalof the catheter body 12, and the basket-shaped electrode assembly 18 atthe distal end of the deflection section 14. The basket-shaped electrodeassembly (or “assembly”) 18 has a plurality of spines 27 whose proximalends and distal ends surround an elongated expander 17 that is affordedlongitudinal movement relative to the catheter for adjusting the shapeof the assembly between an expanded configuration (FIG. 1) and acollapsed configuration (FIG. 2). In the illustrated embodiment of FIG.1, the basket-shaped assembly 18 has at least one region of greater orhyper flexibility, for example, an equatorial region 27E, that enablesthe assembly to deform in a predetermined and predictable manner,including forming a greater or acute flexion at the equatorial region27E and compressing or shortening in the longitudinal direction toabsorb excessive force in the axial direction along longitudinal axis Lof the catheter.

With reference to FIG. 3A, the catheter body 12 comprises an elongatedtubular construction having a single, axial or central lumen 15, but canoptionally have multiple lumens if desired. The catheter body 12 isflexible, i.e., bendable, but substantially non-compressible along itslength. The catheter body 12 can be of any suitable construction andmade of any suitable material. One construction comprises an outer wall20 made of polyurethane or PEBAX® (polyether block amide). The outerwall 20 comprises an imbedded braided mesh of stainless steel or thelike to increase torsional stiffness of the catheter body 12 so that,when the control handle 16 is rotated, the distal end of the catheterbody will rotate in a corresponding manner.

The outer diameter of the catheter body 12 is not critical, but may beno more than about 8 french, more preferably 7 french. Likewise thethickness of the outer wall is not critical, but is preferably thinenough so that the central lumen 15 can accommodate a puller wire, leadwires, sensor cable and any other wires, cables or tubes. If desired,the inner surface of the outer wall is lined with a stiffening tube 21to provide improved torsional stability. An example of a catheter bodyconstruction suitable for use in connection with the present inventionis described and depicted in U.S. Pat. No. 6,064,905, the entiredisclosure of which is incorporated herein by reference.

Distal of the catheter body 12 is the intermediate deflection section 14which comprises a multi-lumened tubing 19, with, for example, at leasttwo off axis lumens 31 and 32, as shown in FIGS. 3A and 3B. Themulti-lumened tubing 19 is made of a suitable non-toxic material that ispreferably more flexible than the catheter body 12. In one embodiment,the material for the tubing 19 is braided polyurethane or thermoplasticelastomer (TPE), for example, polyether block amide (PEBAX®), with animbedded mesh of braided high-strength steel, stainless steel or thelike. The outer diameter of the deflection section 14 is no greater thanthat of the catheter body 12. In one embodiment, the outer diameter isno greater than about 8 french, more preferably about 7 french. Largeror smaller embodiments are possible, as determined by the number ofspines in the basket, if applicable. The size of the lumens is notcritical, so long as the lumens can accommodate the components extendingtherethrough.

A means for attaching the catheter body 12 to the deflection section 14is illustrated in FIG. 3A. The proximal end of the deflection section 14comprises an outer circumferential notch 24 that receives the innersurface of the outer wall 20 of the catheter body 12. The deflectionsection 14 and catheter body 12 are attached by adhesive (e.g.polyurethane glue) or the like. Before the deflection section 14 andcatheter body 12 are attached, however, the stiffening tube 21 isinserted into the catheter body 12. The distal end of the stiffeningtube 21 is fixedly attached near the distal end of the catheter body 12by forming a glue joint (not shown) with polyurethane glue or the like.Preferably, a small distance, e.g., about 3 mm, is provided between thedistal end of the catheter body 12 and the distal end of the stiffeningtube 21 to permit room for the catheter body 12 to receive the notch 24of the deflection section 14. A force is applied to the proximal end ofthe stiffening tube 21, and, while the stiffening tube 21 is undercompression, a first glue joint (not shown) is made between thestiffening tube 21 and the outer wall 20 by a fast drying glue, e.g.Super Glue® Thereafter, a second glue joint (not shown) is formedbetween the proximal ends of the stiffening tube 21 and outer wall 20using a slower drying but stronger glue, e.g. polyurethane.

The basket-shaped electrode assembly 18 is mounted to the distal end ofthe catheter body 12. As shown in FIGS. 1 and 4A, the basket-shapedelectrode assembly 18 comprises a plurality of electrode-carrying spines27 or arms (e.g., between about five to ten, and preferably about eight)mounted, generally evenly-spaced in about 360 radial degrees around theexpander 17 so that the expander forms the center longitudinal axis L ofthe electrode assembly. Each of the spines 27 is attached, directly orindirectly, at its distal end to the distal end of the expander 17. Insome embodiment, the spines 27 are formed from a cylindrical body 28, asshown in FIG. 4C, which has been cut, for example, by laser, to providethe plurality of spines 27 separated by gaps, each having a free distalend. In the illustrated embodiment, a proximal end of the cylindricalbody 28 remains intact to form a proximal stem 28P; however, it isunderstood that a distal stem 28D may also remain intact, as desired orneeded. Accordingly, in these embodiments, each spine may have arectangular cross-section R. As actuated by longitudinal movement of theexpander 17 relative to the catheter, the assembly 18 is adapted toassume an elongated and collapsed configuration with the expander 17extended distally (FIG. 2) and a deployed and radially expandedconfiguration with the expander drawn proximally (FIG. 1). The expander17 comprises a material sufficiently rigid to achieve this function. Inan embodiment, the expander 17 is a wire or tensile member, and a guidetube 23 is provided to surround, protect and guide the expander 17through the control handle 16, the catheter body 12 and the deflectionsection 14. The guide tube 23 is made of any suitable material,including polyimide.

In one embodiment, each spine 27 of the assembly 18 comprises a cabling210 with build-in or embedded lead wires 212, as shown in FIGS. 5A, 5Band 5C. The cabling has a core 218, and a plurality of generally similarwires 212 covered by an insulating layer 216 that enables each wire tobe formed and to function as a conductor 214. The core 218 provides alumen 224 in which can pass other components such as additional leadwire(s), cables, tubing and/or a support structure to shape the cablingas desired.

In the following description, generally similar components associatedwith cabling 210 are referred to generically by their identifyingcomponent numeral, and are differentiated from each other, as necessary,by appending a letter A, B, . . . to the numeral. Thus, wire 212C isformed as conductor 214C covered by insulating layer 216C. Whileembodiments of the cabling may be implemented with substantially anyplurality of wires 212 in the cabling, for clarity and simplicity in thefollowing description cabling 210 is assumed to comprise N wires 212A,212B, 212C, . . . 212N, where N equals at least the number of ringelectrodes on each respective spine of the assembly 18. For purposes ofillustration, insulating layers 216 of wires 212 have been drawn ashaving approximately the same dimensions as conductors 214. In practice,the insulating layer is typically approximately one-tenth the diameterof the wire.

The wires 212 are formed over an internal core 218, which is typicallyshaped as a cylindrical tube, and core 218 is also referred to herein astube 218. The core material is typically selected to be a thermoplasticelastomer such as a polyether block amid (PEBA) or PEBAX® Wires 212 areformed on an outer surface 220 of the core 218 by coiling the wiresaround the tube 218. In coiling wires 212 on the surface 220, the wiresare arranged so that they contact each other in a “close-packed”configuration. Thus, in the case that core 218 is cylindrical, each wire212 on the outer surface is in the form of a helical coil. In the caseof the tube 218 being cylindrical, the close packed arrangement of thehelical coils of wires 212 means that the wires are configured in amulti-start thread configuration. Thus, in the case of the N wires 212assumed herein, wires 212 are arranged in an N-start threadconfiguration around cylindrical tube 218.

In contrast to a braid, all helical coils of wires 212 herein have thesame handedness (direction of coiling). Moreover, wires in braidssurrounding a cylinder are interleaved, so are not in the form ofhelices. Because of the non-helical nature of the wires in braids, evenbraid wires with the same handedness do not have a threaded form, letalone a multi-start thread configuration. Furthermore, because of thelack of interleaving in arrangements of wires in embodiments of thecabling, the overall diameter of the cabling produced is less than thatof cabling using a braid, and the reduced diameter is particularlybeneficial when the cabling is used for a catheter.

Once wires 212 have been formed in the multi-start thread configurationdescribed above, the wires are covered with a protective sheath 222. Theprotective sheath material is typically selected to be a thermoplasticelastomer such as PEBA, for example, 55D PEBAX without additives so thatit is transparent. In that regard, insulating layer of at least one ofwires 212 is colored differently from the colors of the remaining wiresas an aid in identifying and distinguishing the different wires.

The process of coiling wires 212 around the core 218, and then coveringthe wires by the sheath 222 essentially embeds the wires within a wallof cabling 210, the wall comprising the core and the sheath. Embeddingthe wires within a wall means that the wires are not subject tomechanical damage when the cabling is used to form a catheter.Mechanical damage is prevalent for small wires, such as 48AWG wires, ifthe wires are left loose during assembly of a catheter.

In use as a catheter, an approximately cylindrical volume or lumen 224enclosed by the core 218, that is afforded by embedding smaller wires(such as the 48 AWG wires) in the wall, allows at least a portion of thelumen 224 to be used for other components. It is understood that theplurality of wires 212 shown in the drawings is representative only andthat a suitable cabling provides at least a plurality of wires equal toor greater than the plurality of ring electrodes mounted on each cablingor spine of the assembly. Cabling suitable for use with the presentinvention is described in U.S. Publication No. 2014/0309512 and U.S.Publication No. 2014/0305699, the entire disclosures of which areincorporated herein by reference. Each cabling 210 (with embedded leadwires 212) extends from the control handle 16, through the lumen 15 ofthe catheter body 12, and the larger lumen 32 of the tubing 19 of thedeflection section 14, as shown in FIG. 3A.

With reference to FIGS. 6A and 6B, at the proximal end of the assembly18, the cabling 210 (serving as the spines 27 of the assembly 18, andused interchangeably herein) extend through a proximal junction 18P thatincludes an outer tubing 34 that extends a short distance from thedistal end of the tubing 19 of the deflection section 14. The outertubing 34 may be made of any suitable material, for example, PEEK(polyetheretherketone).

In the lumen of the outer tubing 34, a proximal alignment disc 35 formedwith a plurality of through-holes is provided to receive and positionthe cabling 210 and the guide tube 23 of the expander 17 in the outertubing 34. The proximal disc 35 is made of any suitable material,including metal or plastic. In the embodiment of FIGS. 6A and 6B, theproximal disc 35 has an on-axis through-hole 71 for the guide tube 23,and a plurality of off-axis through-holes 70 around a peripheral regionof the disc, with each through-hole guiding a respective cabling 210(only two of which are shown in FIG. 6A for clarity). For example, witheight cabling 210, the through-holes 70 are situated at about 45 radialdegrees around the peripheral region. Where irrigation is desired, thedisc 35 includes another off-axis through-hole 72 which receives adistal end of an irrigation tubing 39 from which fluid passing throughthe tubing 39 exits the catheter. Distal of the disc 35, the lumen ofthe outer tubing 34 is filled and sealed with a suitable glue 37, forexample, epoxy.

The cabling 210 and the expander 17 extend distally from the proximaljunction 18P to form the assembly 18. Each cabling has a predeterminedshape flexibly set by a shape memory member 38 that extends through thelumen 224 in the core 218. As shown in FIG. 3B, selected or all of thelumens 224 of the cores 218 also carry additional lead wires 40 for thearray of microelectrodes 26 on the distal tip 22. Selected lumens 224may also carry cable(s) 36 for electromagnetic location sensor(s)carried in the distal tip 22.

In forming the basket shape, the shape memory members 38 in the cabling210 diverge from the proximal junction 18P and bow outwardly from theexpander 17, and converge at their distal ends at the distal tip 22, asshown in FIG. 4A. The shape memory member 38, e.g., a Nitinol shapemember or wire, is configured to flexibly provide the shape of thebasket-assembly, as known in the art. In one embodiment, the shapememory member 38 of each cabling 210 has a proximal end located near theproximal end of the deflection section 14, and a distal end located inthe distal tip 22, although it is understood that the proximal end maybe located anywhere proximally of the proximal end of the deflectionsection 14 along the length of the cabling 210, as desired orappropriate.

As understood by one skilled in the art, the number of spines 27 orcabling 210 of the assembly 18 can vary as desired depending on theparticular application, so that the assembly 18 has at least two spines,preferably at least three spines, and as many as eight or more spines.As used herein, the term “basket-shaped” in describing the electrodeassembly 18 is not limited to the depicted configuration, but caninclude other designs, such as spherical or egg-shaped designs, thatinclude a plurality of expandable arms connected, directly orindirectly, at their proximal and distal ends.

In accordance with a feature of the present invention, the assembly 18has a structure that facilitates contact with surrounding tissue wallwhile minimizing risk of injury to the tissue wall. In that regard, theassembly has a greater stiffness near its proximal ends and a greaterflexibility therebetween. In some embodiments, one or more spines 27have at least one region with greater flexibility relative to theirproximal and distal regions. As shown in the embodiment of FIG. 4C,spine 27 has an equatorial region 27E with a different configuration(including a different and/or smaller cross section) that enablesgreater flexibility compared to distal region 27D and proximal region27P. For example, the different configuration includes one or moreindented regions or lateral notches 41 defining a lesser width dimensionW (FIGS. 8A and 9A), one or more inner and outer notches 41 defining alesser thickness dimension T (FIGS. 10A and 11B), or a waist region 43defined by both a lesser width dimension and a lesser thicknessdimension (FIGS. 12A and 12B). The notches 41 providing the transitionbetween the different dimensions along the length of the spines may havea continuous or smooth contour (FIGS. 8A and 11A), or it may have adiscontinuous or stepped contour (FIGS. 9A and 10A).

The region of greater flexibility enables the spine to readily deform soas to absorb any additional or excessive force when the assembly 18,including its distal end or the distal tip electrode 22, contacts tissueeither intentionally (such as when an axial force is applied by an EPprofessional to purposefully expand the assembly) or unintentionally(such as when the distal tip electrode 22 encounters anatomyunexpectedly. As illustrated in FIGS. 8B, 9B, 10B, and 11B, the region27E of the spine readily flexes and bows such that the assembly 18 canshorten and collapse longitudinally into a hyper-expanded configuration,as shown in broken lines in FIG. 4A, to minimize the risk of the distaltip electrode 22 causing damage or injury, such as perforation of thetissue wall, without compromising the structure and stiffness of theproximal and distal regions 27P and 27D of the spines. In theillustrated embodiment of FIG. 4A, the equatorial region 27E of greateror hyper flexibility readily deforms and bends to form a greater oracute bend so that the assembly 18 is compressed longitudinally toabsorb a force acting on the assembly from either its distal end or itsproximal end. When compressed, the spines 27 can deform into more of aV-shape configuration with the assembly 18 able to deform and flatteninto a shape resembling a pattypan or scallop squash, as better shown inFIG. 4B (without electrodes for clarity), with a visibly shortenedlongitudinal length and a visibly pronounced ridge-like equatorialregion 27E, with the distal and proximal portions 27D and 27Pexperiencing minimal deformation. Advantageously, the regions of greaterflexibility in the spines allow the spine to readily elastically changebetween a first configuration with a generally uniform flexed curvaturealong its length to a second configuration having a generally uniformcurvature at the distal and proximal regions separated by a hyper ormore acute curvature in an equatorial region.

Each spine 27 or cabling 210 carries a plurality of ring electrodes 240,which may be configured as monopolar or bipolar, as known in the art.FIGS. 5A and 5B are schematic diagrams illustrating attachment of a ringelectrode 240 to cabling 210, according to an embodiment. FIG. 5A is aschematic top view of the cabling and FIG. 5B is a schematic side viewof the cabling; in both views portions of sheath 222 have been cut awayto expose wires 212 of the cabling 210, as well as to illustrate theattachment of a ring electrode 240 to the cabling 210. FIG. 5Aillustrates cabling 210 before attachment of ring electrode 240, andFIG. 5B illustrates the cabling after the ring electrode has beenattached. Ring electrode has dimensions enabling it to be slid oversheath 222.

Initially a location for attaching a ring electrode 240 is selected byvisually finding a colored wire, such as wire 212E. The visualdetermination is possible since sheath 222 is transparent. Once thelocation has been selected, a section of sheath 222 above the wire and acorresponding section of insulating layer 216E are removed to provide apassage 242 to conductor 214E. In a disclosed embodiment, conductivecement 244 is fed into the passage, ring electrode 240 is slid tocontact the cement, and the electrode is then crimped in place.Alternatively, the ring electrode 240 may be attached to a specific wireby pulling the wire through sheath 222, and resistance welding orsoldering the ring electrode to the wire.

With reference to FIGS. 7A and 7B, at the distal end of the assembly 18,the distal ends of the cabling 210 converge around the distal end of theexpander 17 in the distal tip 22. The distal tip 22 has a generallysolid, elongated, nonmetallic, electrically-insulating substrate body 25with a generally cylindrical shape (with a two-dimensional curvature inthe X/Y direction and a linear length in the Z direction), and a domeddistal end (with a three-dimensional curvature in the X/Y/Z direction).The body has a trepanned proximal face 47 forming a cored-out proximalregion 29 in which the distal ends of the cabling 210 and the expander17 are received, anchored and sealed by glue 49, for example, epoxy. Afirst, on-axis blind hole 50 extends distally from the cored-outproximal region to receive a crimped distal tip of the expander 17. Asecond, off axis blind hole 52 extends distally from the cored-outproximal region 29 to receive at least a portion of the electromagneticlocation sensor 42.

The distal ends of the cabling 210 in the cored-out proximal region 29are positioned by a distal alignment disc 45. The disc 45 has aplurality of through-holes to receive the cabling 210 and the expander17 in the outer tubing 34. The disc 45 is made of any suitable material,including metal or plastic. In the embodiment of FIGS. 7A and 7B, thedistal disc 45 has an on-axis through-hole 92 for the expander 17, and aplurality of off-axis through-holes 90 around a peripheral region of thedisc, with each through-hole guiding the distal end of a respectivecabling 210 (only two of which are shown in FIG. 7A for clarity). Forexample, with eight cabling 210, the through-holes 90 are situated atabout 45 radial degrees around the peripheral region. Proximal of thedisc 45, the cored-out proximal region 29 is filled and sealed with asuitable glue 49, for example, epoxy.

Also formed in the body 25 of the distal tip 22 are axial passages 60and radial passages 62, as shown in FIG. 7A, providing communicationbetween the cored-out proximal region 29 and indentations 64 formed onouter surface 33 of the body 25 where the microelectrodes 26 arelocated. With respective pairs of the cabling 210 and axial passages 60axially aligned with each other in the tip 22, the additional lead wires40 that pass through the lumen 224 of the core 218 of the cabling 210extend through the axial and radial passages 60 and 62 for connection tothe respective microelectrodes and/or temperature sensing in the distaltip 22. Radial microelectrodes 26R are located on radial outer surfaceof the body 25. Distal microelectrodes 26D are located on distal outersurface of the body 25. It is understood that the plurality of wires 40shown in the drawings is representative only and that the plurality ofwires is equal to or greater than the plurality of microelectrodescarried on the distal tip 22. Also passing through the lumen 224 of thecore 218 of one predetermined cabling 210′ is the cable 36D for thedistal EM location sensor 42D. A portion of the wall of the cabling 210′is removed at X so as to accommodate the cable 36D extending from adistal EM location sensor 42D.

In accordance with a feature of the present invention, the indentations64 are shaped and sized in correspondence with the shape and size of themicroelectrode 26 which has a body that is fully received in arespective indentation 64 such that only an outer or outer-facingsurface 63 of the microelectrode is exposed and generally even and flushwith the outer surface 33 of the body 25 of the distal tip 22, as shownin FIGS. 7A and 7C. The indentations 64 allow the microelectrodes 26 tobe recessed in the body 25 to provide a smooth and atraumatic profilewhich minimizes the risk of the microelectrodes snagging, scratching orotherwise damaging tissue in contact with the distal tip 22. Eachindentation minimizes, if not prevents, contact between tissue and amicroelectrode except by the outer surface 63 of the microelectrode. Theindentation limits tissue contact by any side surface or inner surfaceof a microelectrode by surrounding the microelectrode except for theouter surface.

Moreover, the outer surface 63 of the microelectrode 26 has the samecontour as the surrounding outer surface 33 of the substrate body 25.For example, the distal microelectrodes 26D have three-dimensionallycurved outer surfaces 63D that conform with the three-dimensionallycurved outer surface 33 of the substrate body 25 at its distal end, andthe radial microelectrodes 26R have two-dimensionally curved outersurfaces 63R that conform with the two-dimensionally curved outersurfaces 33 of the substrate body 25. With a generally smooth profile,the tip 22 can be pivoted about its distal end in a circular motionwhere its longitudinal axis traces a cone C to improve electrode contactwith minimum risk of damage to tissue, especially in a cavernous region,such as an atrium.

Each microelectrode 26 has a surface area ranging between about 0.05 mm²and 0.5 mm², and preferably 0.15 mm². Thus, the distal tip 22 comprisesa plurality of tiny, closely spaced electrodes that may be formed fromany suitable material, including medical-grade metal, for example,palladium, platinum, gold, stainless steel and the like, andcombinations thereof. With a large number of microelectrodes 26, the tip22 advantageously provides focal diagnostic capabilities with preciselyknown microelectrode locations by means of their fixed location relativeto the tip body 25, whereas the assembly 18 with its large number ofring electrodes 240 on the spines 27 allows the physician to morequickly cover a large area of internal geometry of a cavernous region,such as the heart.

Each of the ring electrodes 240 on the spines 27 and each of themicroelectrodes 26 is electrically connected via the lead wires 212 and40, respectively, to an appropriate mapping system and/or source ofablation energy remote from the catheter by means of a multi-pinconnector (not shown) at the proximal end of the control handle 16. Thecabling 210 with embedded electrode lead wires 212 in its wall andadditional lead wires 40 and EM sensor cable 36 in its lumen 224 passfrom the control handle 16 and through the central lumen 15 of thecatheter body 12 and the lumen 32 of the deflection section 14 andextends through the assembly 18 as the spines where lead wires 212 areconnected to the ring electrodes, the lead wires 40 are connected to themicroelectrodes 26 on the distal tip 22 and the cable 36 to the EMsensor in the distal tip 22. By combining the assembly 18 with amicroelectrode distal tip 22, the catheter is adapted for both largearea mapping and acute focal mapping.

The expander 17 has a suitable length that extends the entire length ofthe catheter. The expander includes a proximal end 17P (FIG. 1) that isexposed proximally of the control handle 16, a main portion that extendsthrough the control handle 16, the central lumen 15 of the catheter body12, and the lumen 32 of the deflection section 14, and an exposed distalportion extending through the assembly 18 and into the distal tip 22.The guide tube 23 extends through the control handle 16, the centrallumen 15 of the catheter body, and the lumen 32 of the deflectionsection 14 and has distal end that extends a short distance distal ofthe distal end of the outer tubing 34 of the proximal junction 18P ofthe assembly 18. A user manipulates the proximal end 17P by advancing orwithdrawing the expander 17 longitudinally relative to the controlhandle 16 and the catheter so that it can move the distal ends of thespines 27 proximally or distally relative to the catheter to radiallyexpand and contract, respectively, the assembly 18.

As shown in FIGS. 3A and 3B, a puller wire 48 for uni-directionaldeflection of the deflection section 14 extends from the control handle16 where its proximal end is anchored and responsive to a deflectionknob 13 on the control handle 16, and through the central lumen 15 ofthe catheter body 12 and the lumen 31 of the deflection section 14. Asshown in FIG. 6A, a distal end of the puller wire 48 is anchored nearthe distal end of the deflection section 14 by a T-bar 55 as known inthe art. Along the length of the lumen 15 of the catheter body 12, thepuller wire is surrounded by a compression coil 57, as shown in FIG. 3A.The compression coil has a proximal end at or near a junction betweenthe control handle 16 and the catheter body 12, and a distal end at ornear the distal end of the catheter body 12. Accordingly, when thepuller wire 48 is drawn proximally by manipulation of the deflectionknob 13 (FIG. 1) on the control handle 16, the compression coil 57 stopscompression along its length so that the puller wire 48 deflects thedeflection section 14 distal of the catheter body 12. The catheter mayinclude a second puller wire for bi-directional deflection, as known inthe art.

A distal electromagnetic location sensor 42D is connected to sensorcable 36D that extends through the lumen 224 of selected cabling 210′(FIG. 3B) which extends from the catheter body 12 and control handle 16and out the proximal end of the control handle 16 (FIG. 1) within anumbilical cord (not shown) to a sensor control module (not shown) thathouses a circuit board (not shown). Alternatively, the circuit board canbe housed within the control handle 16, for example, as described inU.S. Pat. No. 6,024,739, the disclosure of which is incorporated hereinby reference. The sensor cable 36D comprises multiple wires encasedwithin a plastic covered sheath. In the sensor control module, the wiresof the sensor cable are connected to the circuit board. The circuitboard amplifies the signal received from the corresponding locationsensor and transmits it to a computer in a form understandable by thecomputer by means of the sensor connector at the proximal end of thesensor control module. Also, because the catheter is designed for singleuse only, the circuit board may contain an EPROM chip that shuts downthe circuit board approximately twenty-four hours after the catheter hasbeen used. This prevents the catheter, or at least the location sensor,from being used twice.

In one embodiment, the location sensor 42D comprises amagnetic-field-responsive coil, as described in U.S. Pat. No. 5,391,199,or a plurality of such coils, as described in International PublicationWO 96/05758. The plurality of coils enables six-dimensional position andorientation coordinates to be determined. Alternatively, any suitablelocation sensor known in the art may be used, such as electrical,magnetic or acoustic sensors. Suitable location sensors for use with thepresent invention are also described, for example, in U.S. Pat. Nos.5,558,091, 5,443,489, 5,480,422, 5,546,951, and 5,568,809, andInternational Publication Nos. WO 95/02995, WO 97/24983, and WO98/29033, the disclosures of which are incorporated herein by reference.In one embodiment, an electromagnetic mapping sensor has a length offrom about 3 mm to about 7 mm, preferably about 4 mm.

A proximal EM location sensor 42P may be provided at the proximal end ofthe assembly 18, as shown in broken lines in FIG. 6A. The sensor 42P ishoused in the outer tubing 34 and a cable 36P, also shown in brokenlines in FIG. 6A, for the proximal location sensor 42P may extendthrough the central lumen 15 of the catheter body 12, and the lumen 32of the deflection section 14. With a second location sensor, thecoordinates of the distal sensor 42D, relative to those of the proximalsensor 42P, are determined and taken together with other knowninformation pertaining to the curvature of the spines 27 of thebasket-shaped mapping assembly 18. This information is used to find thepositions of the ring electrodes 240 mounted on the spines 26.

As would be recognized by one skilled in the art, other arrangements forconstructing the proximal and distal junctions and for mounting thelocation sensors could also be used in accordance with the invention.

To use the catheter of the invention, an electrophysiologist introducesa dilator and a guiding sheath into the patient, as is generally knownin the art. A suitable guiding sheath for use in connection with theinventive catheter is the PREFACE™. Braided Guiding Sheath (commerciallyavailable from Biosense Webster, Inc., Diamond Bar, Calif.). Thecatheter is introduced through the guiding sheath with the expanderextended and the assembly collapsed so that the assembly can be fed intothe guiding sheath. The guiding sheath covers the spines of the assemblyin a collapsed position so that the entire catheter can be passedthrough the patient's vasculature to the desired location. Once theassembly of the catheter reaches the desired location, e.g., the leftatrium, the guiding sheath is withdrawn to expose the assembly. Theexpander is drawn proximally or otherwise manipulated so that the spinesflex outwardly. With the assembly radially expanded, the ring electrodescontact atrial tissue. Using the ring electrodes on the spines incombination with the location sensor(s), the electrophysiologist can maplocal activation time and/or ablate and irrigate as needed, indiagnosing and providing therapy to the patient. With the multipleelectrodes on the assembly, the catheter enables the electrophysiologistto obtain a true anatomy of a cavernous region of the heart, includingan atrium, by measuring more points than with traditional catheters,allowing him to map the region more quickly. Moreover, for focal tissuecontact, the electrophysiologist can direct the distal tip with highdensity microelectrodes for greater location precision and greatersensitivity in detecting more subtle electrical activity of hearttissue.

Where better tissue contact is desired between the electrodes on theassembly 18 and/or the distal tip electrode 22, an axial force FD may beapplied by the EP professional, as shown in FIG. 4A, wherein the spines27 are sufficiently rigid in their distal and proximal regions 27D and27P to ensure tissue contact while the flexible region 27E readilydeforms to absorb and dampen any excessive force that may cause damageto tissue at the distal end of the assembly 18. Similarly, where theassembly 18 is advanced and encounters anatomy at its distal end, therisk of tissue damage by the distal tip electrode 22 is minimized by theflexible region 27E readily deforming to absorb and dampen excessivecompressive force FP.

FIGS. 13A and 13B illustrate another embodiment of the presentinvention, wherein at least one spine 27′ of an assembly 18′ has morethan one region of greater flexibility spanning between regions oflesser flexibility by comparison. In the illustrated embodiment of FIG.13A, a first region of greater flexibility 27A spans between the distalportion 27D and a mid-portion 27M, and a second region of greaterflexibility 27B spans between the mid-portion 27M and the proximalportion 27P. Accordingly, the first and second regions of greater orhyper flexibility 27A and 27B readily deform and bend to form greater oracute bends so that the assembly 18′ is compressed longitudinally toabsorb a force acting on the assembly from either its distal end or itsproximal end, as shown in FIG. 13C. When compressed, the spines 27′generally deform into a U-shape with the assembly 18 deforming more intoa generally cylindrical shape, as shown in FIG. 13D, wherein theassembly is compressed longitudinally with the distal, mid and proximalportions 27D, 27M and 27M experiencing minimal deformation.Advantageously, the regions of greater flexibility in the spines allowthe spine to readily elastically change between a first configurationwith a generally uniform flexed curvature along its length to a secondconfiguration having a generally uniform curvature at the distal, midand proximal regions separated by regions with a hyper or more acutecurvature.

In accordance with another feature of the present invention which may beincorporated in addition to or lieu of one or more other features of thepresent invention, the spines of the basket-shaped electrode assemblymay be constructed with suitable materials, for example, Nitinol alloyswith different As and/or Af, wherein As is the temperature wherematerial starts to transform to austenite upon heating and Af is thetemperature where material has finished transforming to austenite uponheating. In the illustrated embodiment of FIG. 4B, distal and proximalregions 27D and 27P include a first Nitinol alloy with a higher “As,”and at least one region 27E includes a second Nitinol alloy with a lower“As.” Accordingly, the first Nitinol alloy at the distal and proximalregions 27D and 27P begins to exhibits superelastic behavior at a highertemperature upon heating, and the second Nitinol alloy begins toexhibits superelastic behavior at a lower temperature upon heating. Inanother embodiment, the first Nitinol alloy may have a lower Af and thesecond Nitinol alloy may have a higher Af, such that the distal andproximal regions 27D and 27P have a higher temperature at which theyhave finished transforming to austenite upon heating, and the at leastone region 27E has a lower temperature at which it has finishedtransforming to austenite upon heating. With reference to the embodimentof FIG. 13D, the distal, proximal and mid regions 27D, 27P and 27M maybe constructed of the first Nitinol alloy and the regions 27A and 27B ofgreater flexibility may constructed of the second Nitinol alloy.

In accordance with another feature of the present invention which may beincorporated in addition to or lieu of one or more other features of thepresent invention, the spines are surrounded by nonconductive,protective covering or cabling 211 which include regions of differentdurometer or flexibility, as shown in FIGS. 14A and 14B. For example,the covering 211 includes at least one region 211F of greater (or hyper)flexibility (or lower durometer) and at least one region of lesserflexibility 27G. Moreover, the one region of greater flexibility 211Fmay generally align with a spine region of greater (or hyperflexibility) 27F (which may have a smaller cross section as shown inbroken lines), and the one region of lesser flexibility (or higherdurometer) 211G may generally align with a spine region of lesserflexibility (27F), such that the regions of spine and coveringfacilitate each other in flexing.

In accordance with another feature of the present invention, the spines27 are connected, tied or tethered to each other. With reference toFIGS. 15A and 15B, adjacent spines 27 are connected to each other by atensile member 58 that is affixed to the spines 27 generally at theirequatorial region or at the region of greater flexibility. The tensilemember 48 helps to maintain spine and electrode spacing. The tensilemember 58 may comprises individual sections whose ends are affixed totwo adjacent spines, respectively, or it may have a continuous lengthaffixed to each spine with a knot 58N. The tensile member 58 may beelastic or nonelastic, provided the length(s) are sufficient toaccommodate the expanded and hyper-expanded configurations of theassembly.

The preceding description has been presented with reference to presentlydisclosed embodiments of the invention. Workers skilled in the art andtechnology to which this invention pertains will appreciate thatalterations and changes in the described structure may be practicedwithout meaningfully departing from the principal, spirit and scope ofthis invention. As understood by one of ordinary skill in the art, thedrawings are not necessarily to scale and any feature or combinations offeatures described in one embodiment may be incorporated into any otherembodiments or combined with any other feature(s) of another embodiment,as desired or needed. Accordingly, the foregoing description should notbe read as pertaining only to the precise structures described andillustrated in the accompanying drawings, but rather should be readconsistent with and as support to the following claims which are to havetheir fullest and fair scope.

What is claimed is:
 1. A catheter comprising: an elongated catheter bodyhaving proximal and distal ends and at least one lumen therethrough; anda basket-shaped electrode assembly at the distal end of the catheterbody, the basket-shaped electrode assembly having proximal and distalends and comprising a generally cylindrical body having proximal anddistal ends, the generally cylindrical body comprising: a proximal stemportion at the proximal end of the generally cylindrical body, and aplurality of spines extending from the proximal stem portion of thegenerally cylindrical body, at least one of the spines having anequatorial region of greater flexibility and proximal and distal regionsof lesser flexibility, the basket-shaped electrode assembly beingmoveable between a collapsed configuration, an expanded configuration inwhich the spines bow radially outward relative to the catheter body toform a first expanded shape, and a hyper-expanded configuration in whichthe spines bend at the equatorial region of greater flexibility tothereby deform the first expanded shape, shorten a length of thebasket-shaped electrode assembly and assume a V shape with an acute bendin the equatorial region of greater flexibility.
 2. The catheter ofclaim 1, wherein the generally cylindrical body further comprises adistal stem portion, the plurality of spines extending between theproximal stem portion and the distal stem portion.
 3. The catheter ofclaim 1, wherein each of the plurality of spines has a generallyrectangular cross-section.
 4. The catheter of claim 1, wherein theequatorial region of the at least one of the spines has a differentand/or smaller cross-section than the proximal and distal regions. 5.The catheter of claim 1, wherein the at least one of the spines has awidth dimension and a thickness dimension, and the equatorial region ofgreater flexibility has a lesser width and/or a lesser thickness thanthe first and second regions.
 6. The catheter of claim 5, wherein theequatorial region of greater flexibility has a lesser width imparted byone or more indented regions or lateral notches.
 7. The catheter ofclaim 6, wherein the one or more indented regions or lateral notcheshave a continuous contour or a stepped contour.
 8. The catheter of claim5, wherein the equatorial region of greater flexibility has a lesserthickness imparted by one or more inner and/or outer notches.
 9. Thecatheter of claim 8, wherein the one or more inner and/or outer notcheshave a continuous contour or a stepped contour.
 10. The catheter ofclaim 5, wherein the equatorial region of greater flexibility has awaist region imparting both a lesser width and a lesser thickness. 11.The catheter of claim 10, wherein the waist region has a continuouscontour or a stepped contour.
 12. A catheter comprising: an elongatedcatheter body having proximal and distal ends and at least one lumentherethrough; and a basket-shaped electrode assembly at the distal endof the catheter body, the basket-shaped electrode assembly havingproximal and distal ends and comprising a generally cylindrical bodyhaving proximal and distal ends, the generally cylindrical bodycomprising: a proximal stem portion at the proximal end of the generallycylindrical body, and a plurality of spines extending from the proximalstem portion of the generally cylindrical body, at least one of thespines having first and second regions of greater flexibility and a midregion of lesser flexibility between the first and second regions ofgreater flexibility, the basket-shaped electrode assembly being movablebetween a collapsed configuration, an expanded configuration in whichthe spines bow radially outward relative to the catheter body to form afirst expanded shape, and a hyper-expanded configuration in which thespines bend at the first and second regions of greater flexibility tothereby deform the first expanded shape and assume a U shape with firstand second acute bends in the first and second regions of greaterflexibility.
 13. The catheter of claim 12, wherein the generallycylindrical body further comprises a distal stem portion, the pluralityof spines extending between the proximal stem portion and the distalstem portion.
 14. The catheter of claim 12, wherein the at least one ofthe spines has a width dimension and a thickness dimension, and thefirst and second regions of greater flexibility each independently has alesser width and/or a lesser thickness than the mid region.
 15. Thecatheter of claim 14, wherein the first and second regions of greaterflexibility each independently has a lesser width imparted by one ormore indented regions or lateral notches.
 16. The catheter of claim 15,wherein the one or more indented regions or lateral notches have acontinuous contour or a stepped contour.
 17. The catheter of claim 14,wherein the first and second regions of greater flexibility eachindependently has a lesser thickness imparted by one or more innerand/or outer notches.
 18. The catheter of claim 17, wherein the one ormore inner and/or outer notches have a continuous contour or a steppedcontour.
 19. The catheter of claim 14, wherein the first and secondregions of greater flexibility each independently has a waist regionimparting both a lesser width and a lesser thickness.
 20. The catheterof claim 19, wherein the waist region has a continuous contour or astepped contour.